1. Field of the Invention
The invention relates to an image forming apparatus such as a laser printer, and a process cartridge installed in the image forming apparatus.
2. Description of Related Art
An image forming apparatus such as a laser printer includes a combination of a photoconductive drum and a transfer roller which are adjacent to each other to form a pressure nip therebetween, and a combination of a heating roller and a pressing roller which are adjacent to each other to form a pressure nip therebetween and disposed on the downstream side of the combination of the photoconductive drum and transfer roller in a direction in which a recording medium in the form of a sheet of paper is fed along a sheet feeding path. The photoconductive drum carries a toner image formed according to image data. The toner image is transferred onto a paper sheet passing through the nip between the photoconductive drum and the transfer roller to which a transfer bias voltage is being applied. The paper sheet to which the toner image has been transferred is further passed through the nip between the heating roller and pressing roller, being heated by the heating roller and pressed between the heating and pressing rollers, thereby fixing the toner image on the paper sheet. In this way, a desired image is formed on the paper sheet.
In such a kind of image forming apparatus, the paper sheet may wind around any of various kinds of rollers in the image forming apparatus including the transfer roller, heating roller, and pressing roller.
In regard to the heating roller, which is disposed on the side of the sheet feeding path to be opposed to the surface of the paper sheet on which the toner image has been transferred, during the paper sheet with the toner image is passed through between the heating roller and pressing roller, the toner on the paper sheet contacts the heating roller and melts and adheres thereto, causing the paper sheet to wind around the heating roller.
There has been proposed, for instance in JP-A-2001-75391, to provide a separating claw which contacts an outer circumferential surface of a heating unit such as a heating roller to separate a paper sheet from the heating unit, in order to prevent the paper sheet from winding around the heating unit. When such a separating claw is provided, an edge of the paper sheet as being wound around the outer circumferential surface of the heating unit is brought into contact with the separating claw, prevented from further winding around the heating roller. The paper sheet is thus separated from the outer circumferential surface of the heating unit, enabling prevention of winding of the paper sheet around the heating unit.
However, the separating claw disclosed in the above-mentioned publication contacts the outer circumferential surface of the heating roller, and therefore is not suitably used for prevention of winding of a paper sheet around an elastic roller which may be a transfer roller, since when the separating claw contacts an elastic member formed of an elastic material, the separating claw damages the elastic member by cutting into the elastic member or otherwise.